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(11) | EP 0 189 774 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Process for production of N,N-disubstituted carboxylic acid amides |
| (57) A novel process for producing N,N-disubstituted carboxylic acid amides represented
by the following formula
wherein R, R1, R2 and R3 are as defined in claim 1, which comprises contacting a Schiff base represented by
the following formula (III)
R, R1 and R2 are as defined above, with a carboxylic acid derivative represented by the following
formula (III)
R3 is as defined above, and M represents a halogen atom or the moiety
X, Y and Z, independently from each other, represent a hydrogen atom or a halogen atom, in the presence or absence of an inert organic solvent. |
[0001] This invention relates to a novel process for producing N,N-disubstituted carboxylic acid amides of the following formula (I)
wherein R, R1, R2 and R3 are defined below.
[0002] Processes for producing N,N-disubstituted carboxylic acid amides of formula (I) which are useful, for example, as medicines, agricultural chemicals, or starting materials or intermediates for producing them are generally known [see, for example, Japanese Laid-Open Patent Publication No. 4181/1985 laid-open on January 10, 1985; U. S. Patents Nos. 2863752, 4372972, 4282028, 4460603, 4521243, 4494978, 4155744, 4456471, 3586496 and 3367847; R. B. Wagner, H. D. Zook, "Synthetic Organic Chemistry", p. 565 (1953), John Wiley & Sons, Inc.; and A. Venkov, M. Nikolova, N. Mollov, Chem. Ind. (London), p. 808 (1982)].
[0003] The most general industrial process among them comprises reducing a Schiff base of the following formula (II)
wherein R, R1 and R2 are as defined below, and acylating or aroylating the resulting reduction product to form a compound of formula (I). For example, the above-cited Japanese Laid-Open Patent Publication No. 4181/1985 discloses a process for producing N,N-disubstituted carboxylic acid amides by a step of reducing the starting Schiff base and a step of chloroacetylating the resulting reduction product in accordance with the following scheme.
[0004] In the above scheme, A represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or an alkylthio group, and R1, R2 and R3' independently from each other, represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or an alkylthio group.
[0005] Known processes for producing N,N-disubstituted carboxylic acid amides including the above-exemplified process have one or more defects. For example, they have complex manufacturing steps. The compounds used as starting materials or intermediates are difficult to obtain, or are unstable. Furthermore, the yields of the desired compounds are low. These defects make it difficult for the known processes to give the desired compounds in goods yields at low cost by simple manufacturing steps.
[0006] The present inventors have extensively worked on an improvement in conventional industrial processes for producing N,N-disubstituted carboxylic acid amides which essentially comprise the above two steps, and consequently found that by contacting a Schiff base with a carboxylic acid derivative in the presence of a silane compound, the desired N,N-disubstituted carboxylic acid amide can be produced easily in good yields by a one-step process. The investigations of the present inventors have shown that this novel mode of reaction can be applied to the reaction of a wide range of Schiff bases with a wide range of carboxylic acid derivatives.
[0007] According to this invention, there is provided a novel process for producing N,N-disubstituted carboxylic acid amides represented by the following formula (I)
wherein R represents a hydrogen atom, an alkyl group, an alkenyl group, an alkoxy group, an alkenyloxy group, a substituted carbonyl group or a trihalogenomethyl group; Rl, R2 and R3, independently from each other, represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted cycloalkenyl group or a substituted or unsubstituted heterocycloalkyl group; R may further represent a hydrogen atom; and R and R , taken together, may form a substituted or unsubstituted cyclic group together with the carbon atom to which they are bonded,
which comprises contacting a Schiff base represented by the following formula (II)
wherein R, R1 and R are as defined above, with a carboxylic acid derivative represented by the following
formula (III)
wherein R3 is as defined above, and M represents a halogen atom or the moiety
in the presence of a silane compound represented by the following formula (IV)
wherein X, Y and Z, independently from each other, represent a hydrogen atom or a
halogen atom,
in the presence or absence of an inert organic solvent.
[0008] The novel process of this invention can be shown, for example, by the following reaction scheme.
[0009] The mechanism of the reaction by which the desired compound of formula (I) is formed in one step by the above novel process is not entirely clear. One possible mechanism presumed by the present inventors is that the Schiff base (II) and the carboxylic acid derivaive (III) react in the presence of the silane compound (IV) to form an immonium salt-type compound
or its M adduct
as an intermediate which further reacts with the silane compound (IV) to form the desired amide compound. Another possible mechanism is that the Schiff base (II) first reacts with the silane compound (IV) to form an N-silyl compound
after which its acylation or arocylation takes place to form the desired amide compound.
[0010] It should be understood that the above reaction mechanisms are merely presumed, and do not in any way limit the novel process of this invention, and that the process of this invention includes all embodiments in which the desired compound of formula (I) is formed in one step by "contacting of the compound of formula (II) with the compound of formula (III) in the presence of the compound (IV)" which results in the reaction of these three components.
[0011] It has thus been found in accordance with this invention that by the novel mode of reaction, the compound of formula (I) can be produced easily in good yields at low cost with industrial advantage from the compound of formula (II) in one step.
[0012] It is an object of this invention to provide a novel process for producing N,N-disubstituted carboxylic acid amides of formula (I).
[0013] The above and other objects and advantages of this invention will become apparent from the following description.
[0014] According to the process of this invention, the N,N-disubstituted carboxylic acid amides of formula (I) can be produced by contacting the Schiff base of formula (II) with the carboxylic acid derivative of formula (III) in the presence of the silane compound of formula (IV) in the presence or absence of an inert organic solvent.
[0015] In formulae (I) and (II), R represents a hydrogen atom, an alkyl group, an alkenyl group, an alkoxy group, an alkenyloxy group, a substituted carbonyl group or a trihalogenomethyl group.
[0016] The alkyl group may, for example, be an alkyl group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Specific examples include methyl, ethyl, propyl, butyl, pentyl, hexyl and octyl groups. The alkenyl group may, for example, be an alkenyl group having 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms. Specific examples of the alkenyl group are vinyl, allyl, propenyl, butenyl, pentenyl and hexenyl groups. The alkoxy group may, for example, be an alkoxy group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. Specific examples of the alkoxy group are methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy and octoxy groups. The alkenyloxy group may, for example, be an alkenyloxy group having 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms. Specific examples of the alkenyloxy group are vinyloxy, allyloxy, propenyloxy, butenyloxy, pentenyloxy and hexenyloxy groups. Examples of the substituted carbonyl group are alkylcarbonyl groups having alkyl with 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, alkoxycarbonyl groups having alkoxy with 1 to 8, preferably 1 to 4 carbon atoms, and arylcarbonyl groups having substituted or unsubstituted aryl having 6 to 10 carbon atoms. In the above aryl carbonyl groups, examples of the substituent for the substituted aryl include alkyl groups having 1 to 6 carbon atoms, alkenyl groups having 2 to 6 carbon atoms, alkynyl groups having 2 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, alkylthio groups having 1 to 6 carbon atoms, alkoxycarbonyl groups having 1 to 4 carbon atoms in the alkoxy moiety, alkylcarbonyl groups having 1 to 4 carbon atoms in the alkyl moiety, halogen atoms, a cyano group, a nitro group, dialkylamino groups having 1 to 4 carbon atoms in each alkyl group, trihalogenomethyl groups and alkylcarbonyloxy groups having 1 to 4 carbon atoms in the alkyl moiety. Examples of the aryl group having 6 to 10 carbon atoms are phenyl, naphthyl, tetrahydronaphthyl and indanyl groups.
[0017] Thus, specific examples of such substituted carbonyl groups include methylcarbonyl, ethylcarbonyl, propylcarbonyl, butylcarbonyl, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, phenylcarbonyl, naphthylcarbonyl, chlorophenylcarbonyl, bromophenylcarbo- nyl, fluorophenylcarbonyl, dichlorophenylcarbonyl, chloro- fluorophenylcarbonyl, methoxyphenylcarbonyl, ethoxyphenyl- carbonyl, methylthiophenylcarbonyl, cyanophenylcarbonyl, nitrophenylcarbonyl, (methylcarbonyloxy)phenylcarbonyl, (trifluoromethyl)phenylcarbonyl, (diethylamino)phenylcarbonyl, (ethoxycarbonyl)phenylcarbonyl, chloronaphthyl- carbonyl, and ethoxynaphthylcarbonyl groups. Examples of the trihalogenomethyl group for R are trihalogenomethyl groups in which the halogen is selected from Cl, Br, I and F. Specific examples of such trihalogenomethyl groups are trichloromethyl, tribromomethyl and trifluoromethyl groups.
[0018] In formulae (I), (II) and (III), Rl, R2 and R3, independently from each other, represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted cycloalkenyl group or a substituted or unsubstituted heterocycloalkyl group; R may further represent a hydrogen atom; and R and R , taken together, may form a substituted or unsubstituted cyclic group together with the carbon atom to which they are bonded.
[0019] Preferred examples of Rl, R2 and R3 include substituted or unsubstituted alkyl groups having 1 to l5 carbon atoms, preferably 1 to 10 carbon atoms, substituted or unsubstituted alkenyl groups having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, substituted or unsubstituted alkynyl groups having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, substituted or unsubstituted aryl groups having 6 to 20 carbon atoms, preferably 6 to 15 carbon atoms, substituted or unsubstituted heteroaryl groups having 2 to 20 carbon atoms, preferably 2 to 14 carbon atoms, and containing 1 to 4 hetero atoms selected from nitrogen, oxygen and sulfur atoms, substituted or unsubstituted cycloalkyl groups having 3 to 20, preferably 3 to 15 carbon atoms, substituted or unsubstituted cycloalkenyl groups having 3 to 20 carbon atoms, preferably 3 to 15 carbon atoms, and substituted or unsubstituted heterocycloalkyl groups having 2 to 20 carbon atoms, preferably 2 to 15 carbon atoms, and containing 1 to 4 hetero atoms selected from nitrogen, oxygen and sulfur atoms.
[0020] Examples of the substituted or unsubstituted cyclic group formed by R and R together with the carbon atom to which they are bonded include cycloalkyl groups having 4 to 15 carbon atoms, preferably 5 to 10 carbon atoms, and heterocycloalkyl groups having 4 to 15 carbon atoms, preferably 5 to 10 carbon atoms, and containing 1 to 4 nitrogen, oxygen or sulfur atoms. Specific examples of such cyclic groups are cyclopentyl, cyclohexyl, cycloheptyl, pyrrolidyl, piperidyl, tetrahydrofuryl and tetra- hydropyryl groups.
[0021] In the illustrated groups for R1, R2, and R3, examples of substituents which they may have include alkyl groups having 1 to 6 carbon atoms, alkenyl groups having 2 to 6 carbon atoms, alkynyl groups having 2 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, alkylthio groups having 1 to 6 carbon atoms, alkoxycarbonyl groups having 1 to 4 carbon atoms, alkylcarbonyl groups having 1 to 4 carbon atoms, halogen atoms, a cyano group, a nitro group, dialkylamino groups having 1 to 4 carbon atoms in each alkyl moiety, trihalogenomethyl groups and alkylcarbonyloxy groups having 1 to 4 carbon atoms in the alkyl moiety.
[0022] More specific examples of the organic groups R1, R2 and R3 which are widely used industrially are given below.
[0023] The unsubstituted alkyl groups include linear or branched alkyl groups, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and dodecyl.
[0024] The substituted alkyl groups include linear or branched haloalkyl groups such as fluoromethyl, trifluoromethyl, chloromethyl, trichloromethyl, chloroethyl, bromoethyl, fluoropropyl, chloropropyl, chlorobutyl, bromopentyl, chlorohexyl, fluorooctyl, trifluoroethyl and hepta- fluorobutyl; linear or branched alkoxyalkyl groups such as methoxymethyl, methoxyethyl, methoxypropyl, methoxybutyl, methoxypentyl, methoxyhexyl, ethoxymethyl, ethoxyethyl, ethoxypropyl, ethoxybutyl, propoxymethyl, propoxyethyl, propoxypropyl, propoxybutyl, butoxymethyl, butoxyethyl, butoxypropyl, butoxybutyl and pentoxyethyl; phenoxyalkyl groups such as phenoxymethyl, phenoxyethyl, chlorophenoxy- propyl and trichlorophenoxypropyl; cyanoalkyl groups such as cyanoethyl, cyanopropyl and cyanobutyl; nitroalkyl groups such as nitroethyl, nitropropyl, nitrohexyl and nitrodecyl; alkylthioalkyl groups such as methylthiomethyl, methylthioethyl, methylthiopropyl, ethylthiomethyl, ethylthioethyl, ethylthiobutyl and propylthioethyl; arylalkyl groups such as phenylmethyl, phenylethyl, phenylpropyl, methylphenylmethyl and chlorophenylmethyl; heteroarylalkyl groups such as thienylmethyl, thienylethyl, methoxythienyl- methyl, furylmethyl, furylethyl, chlorofurylmethyl, pyrrolylmethyl pyrazolylmethyl and pyrazolylethyl; cycloalkylalkyl groups such as cyclopropylmethyl and cyclohexylethyl; and alkoxycarbonylalkyl groups such as methoxycarbonylmethyl, methoxycarbonylethyl, ethoxycarbonylmethyl, ethoxycarbonylethyl and ethoxycarbonylpropyl.
[0025] The unsubstituted alkenyl groups include various position isomers of ethenyl, propenyl, butenyl, pentenyl, hexenyl and octenyl.
[0026] The substituted alkenyl groups include haloalkenyl groups such as chloroethenyl, fluoroethenyl, bromo- poropenyl, chlorobutenyl, chloropentenyl and fluorohexenyl; alkoxyalkenyl groups such as methoxyethenyl, methoxy- propenyl, ethoxybutenyl, ethoxyhexenyl and propoxybutenyl; and other substituted alkenyl groups including cyano- ethenyl, cyanopropenyl, nitropropenyl, dimethylamino- ethenyl, furylethenyl and methylthiopropenyl.
[0028] The substituted alkynyl groups include chloro- propynyl, bromobutynyl, methoxybutynyl, cyanopropynyl and methylthiobutynyl.
[0030] The substituted aryl groups include alkylphenyl groups such as methylphenyl, dimethylphenyl, ethylphenyl, diethylphenyl, propylphenyl, dipropylphenyl, butylphenyl, pentylphenyl, hexylphenyl, methylethylphenyl, methyl- propylphenyl, ethylpropylphenyl, methylbutylphenyl, di-(bromoethyl)phenyl and (trifluoromethyl)phenyl; halophenyl groups such as fluorophenyl, difluorophenyl, chlorophenyl, dichlorophenyl, bromophenyl, iodophenyl, trichlorophenyl and chlorofluorophenyl; alkoxyphenyl groups such as methoxyphenyl, dimethoxyphenyl, trimethoxyphenyl, ethoxyphenyl, diethoxyphenyl, propoxyphenyl and butoxyphenyl; substituted phenyl groups such as cyanophenyl, nitrophenyl, chloro(methyl)phenyl, chloro(ethoxy)phenyl, methyl(methoxy)-phenyl, methylthiophenyl, trifluoromethylphenyl, bis(chloro- ethylamino)phenyl, nitro(methyl)phenyl, diphenyl, chloro-(dimethyl)phenyl, (dimethylamino)phenyl, ethynylphenyl, chloro(methoxy)phenyl, methyl(propoxy)phenyl, (chloroacetyl)phenyl, methyl(butoxy)phenyl, methylcarbonyloxy- phenyl and acetylpenyl; and substituted naphthyl groups such as methylnaphthyl, dimethylnaphthyl, ethylnaphthyl, chloronaphthyl, dichloronaphthyl, methoxynaphthyl, methyl- thionaphthyl, nitronaphthyl and cyanonaphthyl.
[0031] The unsubstituted heteroaryl groups include furyl, thienyl, pyrrolyl, pyridyl, pyrimidinyl, benzofuryl, benzothienyl, indolyl, quinolyl, thiazolyl, pyrazolyl, benzothiazolyl, thiadiazolyl and oxazolyl.
[0032] The substituted heteroaryl groups include substituted furyl groups such as methylfuryl, dimethylfuryl, ethylfuryl, propylfuryl, chlorofuryl, bromofuryl, methoxy- furyl, ethoxyfuryl, propoxyfuryl, methylthiofuryl, ethyl- thiofuryl and nitrofuryl; substituted thienyl groups such as methylthienyl, ethylthienyl, propylthienyl, butyl- thienyl, fluorothienyl, chlorothienyl, bromothienyl, iodo- thienyl, methoxyethienyl, ethoxythienyl, propoxythienyl, methylthiothienyl, ethylthiothienyl, nitrothienyl, di- chlorothienyl and dimethylthienyl; substituted pyrrolyl groups such as N-methylpyrrolyl, N-ethylpyrrolyl, methyl-N-methylpyrrolyl, chloro-N-ethylpyrrolyl, methoxy-N-methylpyrrolyl, methoxypyrrolyl, ethylpyrrolyl and chloro- pyrrolyl; substituted pyridyl groups methylpyridyl, ethyl- pyridyl, chloropyridyl and methoxypyridyl; substituted benzofuryl groups such as methylbenzofuryl, chlorobenzo- furyl, ethoxybenzofuryl, nitrobenzofuryl, bromo(methoxy)-benzofuryl and chloromethylbenzofuryl; substituted benzothienyl groups such as ethylbenzothienyl, fluorobenzo- thienyl, methoxybenzothienyl, nitrobenzothienyl and chlorobenzothienyl; substituted quinolyl groups such as methylquinolyl, ethylquinolyl, chloroquinolyl and meth- oxyquinolyl; and other substituted heteroaryl groups including methylthiazolyl, methylindolyl, methylpyrimidyl, methylisothiazolyl, ethylcarbazolyl, dimethylpyrrolyl, methylisoxazolyl, phenylisoxazolyl, methoxydihydropyri- midyl, methylthiazolyl, methyloxadiazolyl, N-methyl-(methylthio)triazolyl, methylthiothiadiazolyl, methylthiazolyl, and methylthiazinyl.
[0033] The unsubstituted cycloalkyl groups include cyclopropyl, cyclobutyl, cyclkopentyl and cyclohexyl.
[0034] The substituted cyclkoalkyl groups include methylcyclopropyl, ethylcyclopropyl, propylcyclopropyl, chlorocyclopropyl, methoxycyclopropyl, ethoxycyclopropyl, methylcyclobutyl, bromocyclobutyl, methylthiocyclobutyl, chlorocyclopentyl, methylcyclohexyl, ethylcyclohexyl, chlorocyclohexyl, methoxycyclohexyl, propoxycyclohexyl, dimethylcyclohexyl, dichlorocyclopropyl, chlorocyclohexyl, tetrahydronaphthyl and dihydroindanyl.
[0036] The substituted cycloalkenyl groups include methylcyclobutenyl, chlorocyclopentenyl, methoxycyclo- pentenyl, methylcyclohexenyl, ethylcyclohexenyl, chloro- cyclohexenyl, methoxycyclohexenyl, ethoxycyclohexenyl, trimethylcyclohexenyl, dimethylcyclohexenyl, tetra- methylcyclohexenyl and propenylcyclohexenyl.
[0037] The unsubstituted heterocycloalkyl groups include tetrahydrofuryl, tetrahydrothienyl, pyrrolidyl, tetra- hydropyryl, tetrahydrothiopyryl and piperidyl.
[0038] The substituted heterocycloalkyl groups include N-methylpyrrolidyl, N-ethylpyrrolidyl, N-methylpiperidyl, dihydropyryl, dimethylpiperidyl, dioxolanyl and N-ethyl- piperidyl.
[0039] Compounds having the above-listed groups, in many cases, have various position isomers which may equally be used in the practice of the process of this invention without any particular limitation. For example, the methylphenyl group includes o-methylphenyl, m-methylphenyl and p-methylphenyl groups, and the butyl group includes n-butyl, sec-butyl and tert-butyl groups.
[0040] The substituents are not limited to the above specific examples. Any substituents may be used as required so long as they lead to the formation of the carboxylic acid amides of formula (I) contemplated by the process of this invention.
[0041] The Schiff bases of formula (II) which are preferred in industrial practice may be grouped into the following compounds.
[0042] Compounds of the following formula
wherein E represents 0 or S, R is as defined above, R4, R5, R6 and R7, independently from each other, are the same as defined above for R11 provided that they do not form a cyclic group with R.
[0043] Compounds of the following formula
wherein R is as defined above, and R4, R5, R6, R7, R8 and R9, independently from each other, are the same as defined above for R , provided that they do not form a cyclic group with R.
[0044] Compounds of the following formula
wherein J represents an alkyl, alkoxy, alkoxyalkyl or alkoxycarbonyl group, R is the same as defined above, and R4, R5 and R6, independently from each other, are the same as defined above for R1.
[0045] The following compounds may be cited as specific examples of the Schiff base (II) which can be advantageously used in industrial practice.In the following compounds, Et represents an ethyl group.
[0047] In the silane compound of the following formula (IV)
wherein X, Y and Z, independently from each other, represent a hydrogen atom or a halogen atom, the halogen atom is chlorine, bromine, iodine or fluorine. Chlorine and bromine are preferred. Specific examples of the silane compounds which are preferably used in industrial practice are HSiCl3, HSiBr3, H2SiC12, H2SiBr2 and H3SiBr.
[0048] The carboxylic acid derivative of the following formula
wherein R3 is as defined above and M represents a halogen atom or the moiety
is a carboxylic acid halide when M in formula (III) is a halogen atom. Examples of the halogen atom are fluorine, chlorine, bromine and iodine atoms. For industrial practice, carboxylic acid chlorides or bromides of the above formula in which M is a chlorine or bromine atom are especially preferred. When M represents the moiety
the above formula (III) represents a carboxylic acid anhydride
[0049] Examples of preferred compounds (III) are compounds of the following formulae (III-1) and (111-2).
[0050] Compounds of the formula
wherein M is as defined above, and G represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. Compounds of the formula
wherein M is as defined above, and L represents a phenyl, pyridyl, furyl or benzyl group.
[0051] Examples of the halogen atom for G in formula (III-1) are chlorine, bromine, iodine and fluorine. Examples of the alkyl groups for G are those having 1 to 10 carbon atoms, and examples of the alkoxy group for G are those having 1 to 10 carbon atoms.
[0052] Specific examples of the compound of formula (III) include carboxylic acid halides such as acetyl chloride, acetyl bromide, chloroacetyl chloride, dichloroacetyl chloride, bromoacetyl bromide, iodoacetyl chloride, dibromoacetyl chloride, methoxyacetyl chloride, cyanoacetyl chloride, trifluoroacetyl fluoride, propionyl chloride, chloropropionyl chloride, bromopropionyl bromide, butanoyl chloride, chlorobutanoyl chloride, pentanoyl chloride, chloropentanoyl chloride, hexanoyl chloride, acryloyl chloride, butenoyl chloride, chlorobutenoyl chloride, pentenoyl chloride, chloropentenoyl chloride, propyoyl chloride, phenylpropionyl chloride, phenylpropenoyl chloride, furylacryloyl chloride, benzoyl chloride, benzoyl bromide, methylbenzoyl chloride, ethylbenzoyl bromide, chlorobenzoyl chloride, fluorobenzoyl fluoride, methoxybenzoyl chloride, chloro(methyl)benzoyl chloride, cyanobenzoyl chloride, phenylbenzoyl chloride, nitrobenzoyl chloride, furoyl chloride, thiophenecarboxylic acid chloride, indolecarboxylic acid chloride, picolyl chloride, cyclopropanecarboxylic acid chloride, phenylacetyl chloride, thienylacetyl chloride, dimethylbenzoyl chloride, fluoroacetyl chloride, dibromoacetyl bromide, phenylchloroacetyl chloride, phenyldichloroacetyl chloride, ethoxybutanoyl chloride, cyanopentanoyl chloride, nitro- propionyl bromide, methylthiophenecarboxylic acid chloride, pyrazolylacetyl chloride, pyridinecarboxylic acid chloride, methylthiopyridinecarboxylic acid chloride, acetoacetyl bromide, methylthiopropionyl bromide, bromofuranecarboxylic acid bromide, piperidinecarboxylic acid chloride, ethoxy- carbonylacetyl chloride, heptafluoropropoxytetrafluoropro- pionyl fluoride, imidazolecarboxylic acid chloride, and cinnolinecarboxylic acid chloride; and carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, trifluoroacetic anhydride, chloroacetic anhydride and benzoic anhydride.
[0053] In the practice of the process of this invention, the reaction may be carried out in the presence or absence of a solvent. -Generally, it is preferred to carry it out in an inert organic solvent which does not react with the reactants and the products. Examples of the inert organic solvent include hydrocarbons, halogenated hydrocarbons, and nitriles, such as benzene, toluene, methylene dichloride, chloroform and acetonitrile.
[0054] The amounts of the compounds of formulae (II), (III) and (IV) charged in the practice of the process of this invention can be properly selected. For example, the silane compound of formula (IV) is used in an amount of 0.25 to 2.2 moles per mole of the Schiff base of formula (II). This amount may be varied properly depending upon the number of hydrogen atoms which the silane compound of formula (IV) has. For example, when the silane compound of formula (IV) has one hydrogen atom, its amount is 1 to 2.2 moles. Likewise, its amount is 0.5 to 1.7 moles for 2 hydrogen atoms, 0.34 to 1.5 moles for 3 hydrogen atoms, and 0.25 to 0.8 mole for 4 hydrogen atoms. The amount of the compound of formula (III) is, for example, 1 to 1.2 moles per mole of the Schiff base of formula (II). The amounts of the compounds of formulae (II), (III), and (IV) can be easily set at preferred values by preliminary experiments according to the types of these compounds, the reaction conditions, etc.
[0055] If the carboxylic acid derivative of formula (III) is used in too large an amount, side-reactions sometimes tend to occur. Accordingly, it is preferred to determine the mole ratio of the starting materials experimentally before they are actually used in the process.
[0056] The Schiff base of formula (II), as one starting material used in the invention, needs not to be a purified one. For example, it is possible to synthesize a Schiff base from an aldehyde and an amine by azeotropic dehydration, etc., and the as-synthesized Schiff base can be reacted directly with the silane compound (IV) and the carboxylic acid derivative (III).
[0057] The reaction temperature is not particularly limited, and can be selected from a broad range of temperatures. Preferably, the reaction is carried out at temperatures which are suitable in view of the chemical reactivity of the starting compounds or the stability of the resulting amide compound. Generally, it is selected from a range of -20°C to 150°C. The reaction time, which varies depending upon the reaction temperature, may generally be several minutes to several days, for example 5 minutes to 10 days.
[0058] The sequence of addition of the reactants of formulae (II), (III) and (IV) in the process of this invention is not particularly limited. Generally, the silane compound and the carboxylic acid derivative are added to the Schiff base at room temperature or under cooling. It is also possible to add the Schiff base to a solution of the silane compound and the carboxylic acid derivative. In general, a solvent is frequently used in this reaction. For example, it is possible to add the Schiff base, the silane compound and the carboxylic acid derivative to a solvent, and then react the three compounds in it. Alternatively, the three compounds are dissolved in separate solvents and the solutions are mixed for reaction.
[0059] According to this invention, the carboxylic acid amides of formula (I) can be easily obtained by reacting the starting compounds of formulae (II), (III) and (IV). There is no particular limitation on the method of purifying the compound of formula (I) obtained by the above reaction. Generally, after the reaction, the reaction mixture may be distilled under atmospheric or reduced pressure. As required, washing, recrystallization and chromatography may also be used for purification. When the compound (I) obtained has a high boiling point, low-boiling components such as the solvent are removed, and the residue is again dissolved in a solvent. The solution is washed with water and a dilute aqueous alkaline solution, and then the solvent is removed. As a result, the unreacted silane compound and carboxylic acid derivative, a by-product silane compound, etc. can be easily removed, and the desired compound of formula (I) can be obtained in pure form.
[0060] Specific examples of especially useful N,N-disubstituted carboxylic acid amides of formula (I) obtained by the process of this invention are given below. In the following compounds, Et represents an ethyl group.
[0062] The N,N-disubstituted carboxylic acid amides obtained by the process of this invention are known to be useful as medicines and agricultural chemicaas such as herbicides, insecticides or fungicides and intermediates for the production of the medicines and the agricultural chemicals. Accordingly, they can be used in these known applications without any restriction.
[0063] The process of this invention is an excellent process for producing N,N-disubstituted carboxylic acid amides useful as medicines and agricultural chemicals in good yields from the corresponding Schiff base compounds in one step under mild reaction conditions. After the reaction, the resulting product can be easily purified. Accordingly, the present invention offers an excellent industrial advantage.
[0064] The following Examples illustrate the present invention more specifically. It should be understood that the invention is in no way limited by these examples.
EXAMPLE 1
[0065] A three-necked flask was charged with a solution of 2-(3-methoxy)-thienylmethylidene-2',6'-dimethylaniline (2.49 g) in dry benzene (15 ml), and under a nitrogen atmosphere, a solution of trichlorosilane (2.48 g) in dry benzene (5 ml) was gradually added dropwise with stirring at room temperature. Thereafter, a solution of chloroacetyl chloride (1.22 g) in dry benzene (5 ml) was gradually added, and the mixture was stirred at room temperature for 2 hours. Low-boiling components were removed, and the remaining viscous liquid was again dissolved in benzene (50 ml). The benzene solution was washed with water and then with a dilute aqueous alkaline solution, and dried over anhydrous sodium sulfate. Benzene was removed, and the resulting viscous liquid was dried under vacuum to give a pale brown solid (3.30 g). When distilled, this compound had a boiling point of 172°C/0.15 mmHg.
[0066] The infrared absorption spectrum of this compound showed an absorption at 3100 - 2800 cm-1 assigned to the C-H bond, and a strong absorption at 1670 cm-1 assigned to the carbonyl linkage of the amide group.
[0067] Elemental analysis values were C 59.37%, H 5.89%, and N 4.05%, which well agreed with the calculated values for the composition formula C16H18NSO2Cl (323.84), i.e. C 59.33%, H 5.61% and N 4.33%.
[0068] The mass spectrum of the compound showed a molecular ion peak, M⊕, corresponding to the molecular weight at m/e 323, a peak corresponding to M+-Cl at m/e 288, a peak corresponding to M⊕-COCH2Cl at m/e 246, and a peak corresponding to
at m/e 127 (100%).
[0069] The lH-NMR spectrum (6 ppm; internal standard tetramethylsilane; deuterochloroform solvent) of the compound was also measured. The results were as follows:-
[0070] It shows a singlet at 1.95 ppm for 6 protons corresponding to the methyl protons of (f) substituted at the 2- and 6-positions of the phenyl group; a singlet at 3.50 ppm for 3 protons corresponding to the methyl group of (a); a singlet at 3.72 ppm for 2 protons corresponding to the methylene group of (e); a singlet at 4.75 ppm for 2 protons corresponding to the methylene group of (d); a quadruplet at 6.55 ppm for 2 protons corresponding to the protons of the thiophene ring of (b) and (e); and a multi- plet at 7.00-7.45 ppm for 3 group corresponding to the protons of the benzene ring at (g), (h) and (i).
[0071] The above results led to the determination that the isolated product was N-[2'-(3'-methoxy)-thienylmethyl]-N-chloroaceto-2,6-dimethylanilide. The yield was 93%.
EXAMPLE 2
[0072] The same reaction as in Example 1 was carried out by using acetonitrile as the solvent. After the reaction, low-boiling components were removed, and the resulting viscous liquid was dried in vacuum to form a solid. Recrystallization of the solid from hexane gave N-[2'-(3'-methoxy)-thienylmethyl]-N-chloroaceto-2,6-dimethylanilide as white crystals in a yield of 55%.
EXAMPLE 3
[0073] A solution of 2-(N-methylpyrrolyl)-methylidene-2',6'-diethylaniline (2.40 g) in dry benzene (20 ml) was put in a flask. Under a nitrogen atmosphere, a solution of chloroacetyl chloride (1.42 g) in dry benzene (5 ml) was gradually added with stirring at room temperature. Thereafter, a solution of trichlorosilane (2.38 g) in dry benzene (10 ml) was added. After the addition, the mixture was heated with stirring for 1 hour over an oil bath (50°C). Low-boiling components were removed under reduced pressure, and the resulting viscous liquid was purified by column chromatography to give N'-[2-(N-methylpyrrolyl) methyl]-N'-chloroaceto-2',6'-diethylanilide of the following formula as a pale brown solid in a yield of 64%.
EXAMPLE 4
[0074] A mixture of n-hexylaldehyde (1.53 g), 2,6-diethylaniline (2.24 g) and benzene (50 ml) was heated under reflux for 1 hour over an oil bath to perform azeotropic dehydration. To the resulting solution were added a solution of chloroacetyl chloride (1.79 g) in dry benzene (5 ml) and then a solution of trichlorosilane (3.40 g) in dry benzene (5 ml) with stirring at room temperature. After the addition, the mixture was heated with stirring for 2 hours over an oil bath (40°C). Low-boiling components were removed under reduced pressure, and the resulting viscous liquid was dissolved in ether (50 ml). The ether solution was washed with water, and dried over anhydrous sodium sulfate. Ether was removed, and the resulting liquid was distilled to form N-(n-hexyl)-N-chloro- aceto-2,6-diethylanilide of the following formula having a boiling point of 152°C/0.2 mmHg in a yield of 55% based on 2,6-diethylaniline.
EXAMPLE 5
[0075] In the same way as in Examples 1, 2 and 3, various amide compounds were synthesized using trichlorosilane as the silane compound. The structural formulae, properties and yields of the resulting N,N-disubstituted carboxylic acid amides are summarized in Table 1.
EXAMPLE 6
[0076] By the same method as described in Examples 1 to 4, N,N-disubstituted carboxylic acid amide compounds were synthesized by using various Schiff bases, silane compounds and carboxylic acid derivatives. The structural formulae and yields of the resulting amide compounds are summarized in Table 2.
EXAMPLE 7
1. A process for producing N,N-disubstituted carboxylic acid amides represented by
the following formula (1)
wherein R represents a hydrogen atom, an alkyl group, an alkenyl group, an alkoxy group, an alkenyloxy group, a substituted carbonyl group or a trihalogenomethyl group; R1, R2 and R3, independently from each other, represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted cycloalkenyl group or a substituted or unsubstituted heterocycloalkyl group; R1 may further represent a hydrogen atom; and R and R1, taken together, may form a substituted or unsubstituted cyclic group together with the carbon atom to which they are bonded,
wherein R represents a hydrogen atom, an alkyl group, an alkenyl group, an alkoxy group, an alkenyloxy group, a substituted carbonyl group or a trihalogenomethyl group; R1, R2 and R3, independently from each other, represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted cycloalkenyl group or a substituted or unsubstituted heterocycloalkyl group; R1 may further represent a hydrogen atom; and R and R1, taken together, may form a substituted or unsubstituted cyclic group together with the carbon atom to which they are bonded,
which comprises contacting a Schiff base represented by the following formula (II)
wherein R, R1 and R2 are as defined above, with a carboxylic acid derivative represented by the following
formula (III)
wherein R is as defined above, and M represents a halogen atom or the moiety -OCR3,
in the presence of a silane compound represented by the following formula (IV)
wherein X, Y and Z, independently from each other, represent a hydrogen atom or a
halogen atom,
in the presence or absence of an inert organic solvent.
2. The process of claim 1 wherein the contacting is carried out at a temperature in
the range of -20°C to 150°C.
3. The process of claim 1 wherein the amount of the carboxylic acid derivative of
formula (III) is 1 to 1.2 moles, and the amount of the silane compound of formula
(IV) is 0.25 to 2.2 moles, both per mole of the Schiff base of formula (II).
4. The process of claim 1 wherein the Schiff base of formula (II) is selected from
the group consisting of
compounds of the following formula
wherein E represents 0 or S, R is as defined above, R4, R5, R6 and R7, independently from each other, are the same as defined above for R1, compounds of the following formula
wherein R is as defined above, and R4, R5, R6, R7, R8 and R9, independently from each other, are the same as defined above for Rl,
compounds of the following formula
wherein J represents an alkyl group, an alkoxy group, an alkoxyalkyl group or an alkoxycarbonyl
group, R is the same as defined above, and R4, R5 and R6, independently from each other, are the same as defined above for R1.
5. The process of claim 1 wherein the carboxylic acid derivative of formula (III)
is selected from the group consisting of
compounds of the formula
wherein M is as defined above, and G represents a hydrogen atom, a halogen atom, an
alkyl group or an alkoxy group.
Compounds of the formula
wherein M is as defined, and L represents a phenyl group, a pyridyl group, a furyl
group or a benzyl group.
6. The process of claim 1 wherein R is a member selected from the class consisting
of a hydrogen atom, alkyl groups having 1 to 10 carbon atoms, alkenyl groups having
2 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, alkenyloxy groups having
2 to 6 carbon atoms, alkylcarbonyl groups having 1 to 8 carbon atoms in the alkyl
moiety, alkoxycarbonyl groups having 1 to 8 carbon atoms in the alkoxy moiety, arylcarbonyl
groups having substituted or unsubstituted C6-C10 aryl, said substituent for aryl being selected from alkyl groups having 1 to 6 carbon
atoms, alkenyl groups having 2 to 6 carbon atoms, alkynyl groups having 2 to 6 carbon
atoms, alkoxy groups having 1 to 6 carbon atoms, alkylthio groups having 1 to 6 carbon
atoms, alkoxycarbonyl groups having 1 to 4 carbon atoms in the alkoxy moiety, alkylcarbonyl
groups having 1 to 4 carbon atoms in the alkyl moiety, halogen atoms, a cyano group,
a nitro group, dialkylamino groups having 1 to 4 carbon atoms in each alkyl moiety,
trihalogenomethyl groups and alkylcarbonyloxy groups having 1 to 4 carbon atoms in
the alkyl moiety, and trihalogenomethyl groups in which the halogen is selected from
Cl, Br and F.
7. The process of claim 1 wherein each of R1, R and R3 is a member selected from the class consisting of substituted or unsubstituted alkyl
groups having 1 to 15 carbon atoms, substituted or unsubstituted alkenyl groups having
2 to 15 carbon atoms, substituted or,unsubstituted alkynyl groups having 2 to 15 carbon
atoms, substituted or unsubstituted aryl groups having 6 to 20 carbon atoms, substituted
or unsubstituted heteroaryl groups having 2 to 20 carbon atoms and 1 to 4 hetero atoms
selected from N, N, O and S, substituted or unsubstituted cycloalkyl groups having
3 to 20 carbon atoms, substituted or unsubstituted cycloalkenyl groups having 3 to
20 carbon atoms and substituted or unsubstituted heterocycloalkyl groups having 2
to 20 carbon atoms and 1 to 4 hetero atoms selected from N, O and S; R1 may further represent a hydrogen atom; R and R1, taken together, may form a substituted or unsubstituted C4-C15 cycloalkyl group, or a heterocycloalkyl group, together with the carbon atom to which
they are bonded; and the substituents in said substituted groups are selected from
alkyl groups having 1 to 6 carbon atoms, alkenyl groups having 2 to 6 carbon atoms,
alkynyl groups having 2 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms,
alkylthio groups having 1 to 6 carbon atoms, alkoxycarbonyl groups having 1 to 4 carbon
atoms in the alkoxy moiety, alkylcarbonyl groups having 1 to 4 carbon atoms in the
alkyl moiety, halogen atoms, a cyano group, a nitro group, dialkylamino groups having
1 to 4 carbon atoms in each alkyl moiety, trihalogenomethyl groups and alkylcarbonyloxy
groups having 1 to 4 carbon atoms in the alkyl moiety.